NO.PZ2018062017000024
问题如下：
The following exhibit presents consumption basket and prices over two months:
Over the two-month time period,which kind of price index will lead to the lowest calculated inflation rate?
选项：
A.Laspeyres Index.
B.Paasche Index.
C.Fisher Index.
解释：
B is correct.
Under constant consumption basket(Laspeyres Index)
January consumption basket=20*2.5+25*3=125
February consumption basket=20*3+25*4=160
Inflation rate=(160/125)-1=28%
Under current consumption basket(Paasche Index)
January consumption basket=25*2.5+15*3=107.5
February consumption basket=25*3+15*4=135
(135/107.5)-1=25.58%
Value of the Fisher Index=(128*125.58)^0.5= 126.78
Inflation rate=(126.78/100)-1=26.78%
So using a current consumption basket will lead to the lowest inflation rate.
考点：Inflation Measurement
解析：在拉氏指数法下，应该是用基期的消费篮子:
1月物价水平：20*2.5+25*3=125
2月物价水平：20*3+25*4=160
通胀指数：Inflation rate=(160/125)-1=28%
在沠许指数法下,应该是用当期的消费篮子：
1月的物价水平：25*2.5+15*3=107.5
2月的物价水平：25*3+15*4=135
通胀指数：(135/107.5)-1=25.58%
费雪指数：(128*125.58)^0.5= 126.78
通胀指数：(126.78/100)-1=26.78%
由此可见B选项正确。
请问费雪应该怎么算？
